Commit Graph

11 Commits

Author SHA1 Message Date
Ed Schouten
edcf7fbf59 Don't forget to invoke pre_execve() and post_execve().
CloudABI's proc_exec() was implemented before r282708 introduced
pre_execve() and post_execve(). Sync up by adding these missing calls.
2015-08-17 13:07:12 +00:00
Ed Schouten
2c20fbe43a Use CAP_EVENT instead of CAP_PDWAIT.
The cloudlibc pdwait() function ends up using FreeBSD's kqueue() in
combination with EVFILT_PROCDESC. This depends on CAP_EVENT -- not
CAP_PDWAIT.

Obtained from:	https://github.com/NuxiNL/freebsd
2015-08-12 11:07:03 +00:00
Ed Schouten
aaf53ab2aa Correct the previous commit: remove the DECLARE_MODULE().
It looks like a MODULE_VERSION() can also appear on its own -- there is
no need to use explicitly use DECLARE_MODULE(). Looking at other
modules, this seems common practice.
2015-08-05 16:53:49 +00:00
Ed Schouten
b6efa27589 Add DECLARE_MODULE() to the "cloudabi" kernel module.
This kernel module does not require any explicit initialization, but a
module declaration is needed to let the "cloudabi64" kernel module
automatically pull this in.

Obtained from:	https://github.com/NuxiNL/freebsd
2015-08-05 16:45:47 +00:00
Ed Schouten
367a13f905 Limit rights on process descriptors.
On CloudABI, the rights bits returned by cap_rights_get() match up with
the operations that you can actually perform on the file descriptor.

Limiting the rights is good, because it makes it easier to get uniform
behaviour across different operating systems. If process descriptors on
FreeBSD would suddenly gain support for any new file operation, this
wouldn't become exposed to CloudABI processes without first extending
the rights.

Extend fork1() to gain a 'struct filecaps' argument that allows you to
construct process descriptors with custom rights. Use this in
cloudabi_sys_proc_fork() to limit the rights to just fstat() and
pdwait().

Obtained from:	https://github.com/NuxiNL/freebsd
2015-07-31 10:21:58 +00:00
Ed Schouten
62c31cffae Make forking of CloudABI processes work.
Just like FreeBSD+Capsicum, CloudABI uses process descriptors. Return
the file descriptor number to the parent process.

To the child process we both return a special value for the file
descriptor number (CLOUDABI_PROCESS_CHILD). We also return the thread ID
of the new thread in the copied process, so the threading library can
reinitialize itself.

Obtained from:	https://github.com/NuxiNL/freebsd
2015-07-20 13:46:22 +00:00
Konstantin Belousov
b4490c6e93 The si_status field of the siginfo_t, provided by the waitid(2) and
SIGCHLD signal, should keep full 32 bits of the status passed to the
_exit(2).

Split the combined p_xstat of the struct proc into the separate exit
status p_xexit for normal process exit, and signalled termination
information p_xsig.  Kernel-visible macro KW_EXITCODE() reconstructs
old p_xstat from p_xexit and p_xsig.  p_xexit contains complete status
and copied out into si_status.

Requested by:	Joerg Schilling
Reviewed by:	jilles (previous version), pho
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
2015-07-18 09:02:50 +00:00
Ed Schouten
457f7e23b1 Implement CloudABI's exec() call.
Summary:
In a runtime that is purely based on capability-based security, there is
a strong emphasis on how programs start their execution. We need to make
sure that we execute an new program with an exact set of file
descriptors, ensuring that credentials are not leaked into the process
accidentally.

Providing the right file descriptors is just half the problem. There
also needs to be a framework in place that gives meaning to these file
descriptors. How does a CloudABI mail server know which of the file
descriptors corresponds to the socket that receives incoming emails?
Furthermore, how will this mail server acquire its configuration
parameters, as it cannot open a configuration file from a global path on
disk?

CloudABI solves this problem by replacing traditional string command
line arguments by tree-like data structure consisting of scalars,
sequences and mappings (similar to YAML/JSON). In this structure, file
descriptors are treated as a first-class citizen. When calling exec(),
file descriptors are passed on to the new executable if and only if they
are referenced from this tree structure. See the cloudabi-run(1) man
page for more details and examples (sysutils/cloudabi-utils).

Fortunately, the kernel does not need to care about this tree structure
at all. The C library is responsible for serializing and deserializing,
but also for extracting the list of referenced file descriptors. The
system call only receives a copy of the serialized data and a layout of
what the new file descriptor table should look like:

    int proc_exec(int execfd, const void *data, size_t datalen, const int *fds,
              size_t fdslen);

This change introduces a set of fd*_remapped() functions:

- fdcopy_remapped() pulls a copy of a file descriptor table, remapping
  all of the file descriptors according to the provided mapping table.
- fdinstall_remapped() replaces the file descriptor table of the process
  by the copy created by fdcopy_remapped().
- fdescfree_remapped() frees the table in case we aborted before
  fdinstall_remapped().

We then add a function exec_copyin_data_fds() that builds on top these
functions. It copies in the data and constructs a new remapped file
descriptor. This is used by cloudabi_sys_proc_exec().

Test Plan:
cloudabi-run(1) is capable of spawning processes successfully, providing
it data and file descriptors. procstat -f seems to confirm all is good.
Regular FreeBSD processes also work properly.

Reviewers: kib, mjg

Reviewed By: mjg

Subscribers: imp

Differential Revision: https://reviews.freebsd.org/D3079
2015-07-16 07:05:42 +00:00
Ed Schouten
f9675092b8 Let proc_raise() call into pksignal() directly.
Summary:
As discussed with kib@ in response to r285404, don't call into
kern_sigaction() within proc_raise() to reset the signal to the default
action before delivery. We'd better do that during image execution.

Change the code to simply use pksignal(), so we don't waste cycles on
functions like pfind() to look up the currently running process itself.

Test Plan:
This change has also been pushed into the cloudabi branch on GitHub. The
raise() tests still seem to pass.

Reviewers: kib

Reviewed By: kib

Subscribers: imp

Differential Revision: https://reviews.freebsd.org/D3076
2015-07-14 12:16:14 +00:00
Ed Schouten
4f1905177a Implement normal and abnormal process termination.
CloudABI does not provide an explicit kill() system call, for the reason
that there is no access to the global process namespace. Instead, it
offers a raise() system call that can at least be used to terminate the
process abnormally.

CloudABI does not support installing signal handlers. CloudABI's raise()
system call should behave as if the default policy is set up. Call into
kern_sigaction(SIG_DFL) before calling sys_kill() to force this.

Obtained from:	https://github.com/NuxiNL/freebsd
2015-07-11 19:41:31 +00:00
Ed Schouten
6d338f9a81 Import the CloudABI datatypes and create a system call table.
CloudABI is a pure capability-based runtime environment for UNIX. It
works similar to Capsicum, except that processes already run in
capabilities mode on startup. All functionality that conflicts with this
model has been omitted, making it a compact binary interface that can be
supported by other operating systems without too much effort.

CloudABI is 'secure by default'; the idea is that it should be safe to
run arbitrary third-party binaries without requiring any explicit
hardware virtualization (Bhyve) or namespace virtualization (Jails). The
rights of an application are purely determined by the set of file
descriptors that you grant it on startup.

The datatypes and constants used by CloudABI's C library (cloudlibc) are
defined in separate files called syscalldefs_mi.h (pointer size
independent) and syscalldefs_md.h (pointer size dependent). We import
these files in sys/contrib/cloudabi and wrap around them in
cloudabi*_syscalldefs.h.

We then add stubs for all of the system calls in sys/compat/cloudabi or
sys/compat/cloudabi64, depending on whether the system call depends on
the pointer size. We only have nine system calls that depend on the
pointer size. If we ever want to support 32-bit binaries, we can simply
add sys/compat/cloudabi32 and implement these nine system calls again.

The next step is to send in code reviews for the individual system call
implementations, but also add a sysentvec, to allow CloudABI executabled
to be started through execve().

More information about CloudABI:
- GitHub: https://github.com/NuxiNL/cloudlibc
- Talk at BSDCan: https://www.youtube.com/watch?v=SVdF84x1EdA

Differential Revision:	https://reviews.freebsd.org/D2848
Reviewed by:	emaste, brooks
Obtained from:	https://github.com/NuxiNL/freebsd
2015-07-09 07:20:15 +00:00